Semiconductor processing apparatus having lift and tilt mechanism

ABSTRACT

A lift/tilt assembly for use in a semiconductor wafer processing device is set forth. The lift/tilt assembly includes a linear way comprising a fixed frame and a moveable frame. A nest for accepting a plurality of semiconductor wafers is rotatably connected to the moveable frame. The nest rotates between a wafer-horizontal orientation and a wafer-vertical orientation as it is driven with the movable frame by a motor that is coupled to the linear way. A lever connected to the nest provides an offset from true vertical for the nest when the nest is in the wafer-vertical orientation.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation-in-part of U.S. Ser.No. ______ (Corporate Docket No. P96-0018) and of U.S. Ser. No. ______(Corporate Docket No. P96-0016) which are hereby incorporated byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not Applicable

BACKGROUND OF THE INVENTION

[0003] In the production of semiconductor integrated circuits and othersemiconductor articles from semiconductor wafers, it is often necessaryto provide multiple metal layers on the wafer to serve as interconnectmetallization which electrically connects the various devices on theintegrated circuit to one another. Traditionally, aluminum has been usedfor such interconnects, however, it is now recognized that coppermetallization may be preferable.

[0004] The application of copper onto semiconductor wafers has, inparticular, proven to be a great technical challenge. At this timecopper metallization has not achieved commercial reality due topractical problems of forming copper layers on semiconductor devices ina reliable and cost efficient manner. This is caused, in part, by therelative difficulty in performing reactive ion etching or otherselective removal of copper at reasonable production temperatures. Theselective removal of copper is desirable to form patterned layers andprovide electrically conductive interconnects between adjacent layers ofthe wafer or other wafer.

[0005] Because reactive ion etching cannot be efficiently used, theindustry has sought to overcome the problem of forming patterned layersof copper by using a damascene electroplating process where holes, morecommonly called vias, trenches and other recesses are used in which thepattern of copper is desired. In the damascene process, the wafer isfirst provided with a metallic seed layer which is used to conductelectrical current during a subsequent metal electroplating step. Theseed layer is a very thin layer of metal which can be applied using oneor more of several processes. For example, the seed layer of metal canbe laid down using physical vapor deposition or chemical vapordeposition processes to produce a layer on the order of 1000 angstromsthick. The seed layer can advantageously be formed of copper, gold,nickel, palladium, and most or all other metals. The seed layer isformed over a surface which is convoluted by the presence of the vias,trenches, or other device features which are recessed. This convolutednature of the exposed surface provides increased difficulties in formingthe seed layer in a uniform manner. Nonuniformities in the seed layercan result in variations in the electrical current passing from theexposed surface of the wafer during the subsequent electroplatingprocess. This in turn can lead to nonuniformities in the copper layerwhich is subsequently electroplated onto the seed layer. Suchnonuniformities can cause deformities and failures in the resultingsemiconductor device being formed.

[0006] In damascene processes, the copper layer that is electroplatedonto the seed layer is in the form of a blanket layer. The blanket layeris plated to an extent which forms an overlying layer, with the goal ofcompletely providing a copper layer that fills the trenches and vias andextends a certain amount above these features. Such a blanket layer willtypically be formed in thicknesses on the order of 10,000-15,000angstroms (1-1.5 microns).

[0007] The damascene processes also involve the removal of excess metalmaterial present outside of the vias, trenches or other recesses. Themetal is removed to provide a resulting patterned metal layer in thesemiconductor integrated circuit being formed. The excess platedmaterial can be removed, for example, using chemical mechanicalplanarization. Chemical mechanical planarization is a processing stepwhich uses the combined action of a chemical removal agent and anabrasive which grind and polish the exposed metal surface to removeundesired parts of the metal layer applied in the electroplating step.

[0008] Automation of the copper electroplating process has been elusive,and there is a need in the art for improved semiconductor platingsystems which can produce copper layers upon semiconductor articleswhich are uniform and can be produced in an efficient and cost-effectivemanner. More particularly, there is a substantial need to provide acopper plating system that is effectively and reliably automated.

BRIEF SUMMARY OF THE INVENTION

[0009] A lift/tilt assembly for use in a semiconductor wafer processingdevice is set forth. The lift/tilt assembly includes a linear waycomprising a fixed frame and a moveable frame. A nest for accepting aplurality of semiconductor wafers is rotatably connected to the moveableframe. The nest rotates between a wafer-horizontal orientation and awafer-vertical orientation as it is driven with the movable frame by amotor that is coupled to the linear way. A lever connected to the nestprovides an offset from true vertical for the nest when the nest is inthe wafer-vertical orientation.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0010]FIG. 1 is an isometric view of the semiconductor wafer processingtool in accordance with the present invention.

[0011]FIG. 2 is a cross-sectional view taken along line 2-2 of thesemiconductor wafer processing tool shown in FIG. 1.

[0012]FIGS. 3-8 are a diagrammatic representation of a wafer cassetteturnstile and elevator of a preferred interface module of thesemiconductor wafer processing tool according to the present inventionoperating to exchange wafer cassettes between a hold position and anextraction position.

[0013]FIG. 9 is an isometric view of a preferred wafer cassette trayengageable with the turnstile of an interface module of thesemiconductor wafer processing tool.

[0014]FIGS. 10-15 illustrate one manner in which the processing tool maybe modularized to facilitate end-to-end connection of sequentialprocessing units.

[0015]FIGS. 16-19 illustrate a wafer conveying system in accordance withone embodiment of the present invention.

[0016]FIGS. 20-25 illustrate a further wafer conveying system inaccordance with a further embodiment of the present invention.

[0017]FIG. 26 is a functional block diagram of an embodiment of acontrol system of the semiconductor wafer processing tool.

[0018]FIG. 27 is a functional block diagram of a master/slave controlconfiguration of an interface module control subsystem for controlling awafer cassette interface module.

[0019]FIG. 28 is a functional block diagram of an interface modulecontrol subsystem coupled with components of a wafer cassette interfacemodule of the processing tool.

[0020]FIG. 29 is a functional block diagram of a wafer conveyor controlsubsystem coupled with components of a wafer conveyor of the processingtool.

[0021]FIG. 30 is a functional block diagram of a wafer processing modulecontrol subsystem coupled with components of a wafer processing moduleof the processing tool.

[0022]FIG. 31 is a functional block diagram of a slave processor of theinterface module control subsystem coupled with components of a waferinterface module of the processing tool.

[0023]FIG. 32 is a functional block diagram of a slave processor of thewafer conveyor control subsystem coupled with components of a waferconveyor of the processing tool.

[0024]FIG. 33 is a cross-sectional view of a processing station for usein electroplating a downward facing surface of a semiconductor wafer.

[0025]FIG. 34 illustrates a view of a lift/tilt assembly including anest connected to a linear way.

[0026]FIG. 35 illustrates another view of a lift/tilt assembly includinga nest oriented in a wafer-vertical position and a loaded wafercassette.

[0027]FIGS. 36-38 show section views of a lift/tilt assembly with thelinear way located at three translational locations.

[0028]FIG. 39 illustrates a view of an H-bar assembly that may be usedwith a nest.

[0029]FIG. 40 shows the orientation of a tilt sensor connected to anest.

[0030]FIG. 41 illustrates a laser mapping system that may be used todetect the presence or absence of wafers in a wafer cassette.

[0031]FIG. 42 illustrates a view of a lift/tilt assembly in which thenest has extended vertically past a laser mapping system.

DETAILED DESCRIPTION OF THE INVENTION

[0032] Referring to FIG. 1, a present preferred embodiment of thesemiconductor wafer processing tool 10 is shown. The processing tool 10may comprise an interface section 12 and processing section 14.Semiconductor wafer cassettes 16 containing a plurality of semiconductorwafers, generally designated W, may be loaded into the processing tool10 or unloaded therefrom via the interface section 12. In particular,the wafer cassettes 16 are preferably loaded or unloaded through atleast one port such as first port 32 within a front outwardly facingwall of the processing tool 10. An additional second port 33 may beprovided within the interface section 12 of the processing tool 10 toimprove access and port 32 may be utilized as an input and port 33 maybe utilized as an output.

[0033] Respective powered doors 35, 36 may be utilized to cover accessports 32, 33 thereby isolating the interior of the processing tool 10from the clean room. Each door 35, 36 may comprise two portions. Theupper portions and lower portion move upward and downward, respectively,into the front surface of the processing tool 10 to open ports 32, 33and permit access therein.

[0034] Wafer cassettes 16 are typically utilized to transport aplurality of semiconductor wafers. The wafer cassettes 16 are preferablyoriented to provide the semiconductor wafers therein in an upright orvertical position for stability during transportation of thesemiconductor wafers into or out of the processing tool 10.

[0035] The front outwardly facing surface of the processing tool 10 mayadvantageously join a clean room to minimize the number of harmfulcontaminants which may be introduced into the processing tool 10 duringinsertion and removal of wafer cassettes 16. In addition, a plurality ofwafer cassettes 16 may be introduced into processing tool 10 or removedtherefrom at one time to minimize the opening of ports 32, 33 andexposure of the processing tool 10 to the clean room environment.

[0036] The interface section 12 joins a processing section 14 of theprocessing tool 10. The processing section 14 may include a plurality ofsemiconductor wafer processing modules for performing varioussemiconductor process steps. In particular, the embodiment of theprocessing tool 10 shown in FIG. 1 includes a plating module 20 defininga first lateral surface of the processing section 14. The processingsection 14 of the tool 10 may advantageously include additional modules,such as pre-wet module 22 and resist strip module 24, opposite theplating module 20.

[0037] Alternatively, other modules for performing additional processingfunctions may also be provided within the processing tool 10. Thespecific processing performed by processing modules of the processingtool 10 may be different or of similar nature. Various liquid andgaseous processing steps can be used in various sequences. Theprocessing tool 10 is particularly advantageous in allowing a series ofcomplex processes to be run serially in different processing modules setup for different processing solutions. All the processing can beadvantageously accomplished without human handling and in a highlycontrolled working space 11, thus reducing human operator handling timeand the chance of contaminating the semiconductor wafers.

[0038] The processing modules of the process tool 10 are preferablymodular, interchangeable, stand-alone units. The processing functionsperformed by the processing tool 10 may be changed after installation ofthe processing tool 10 increasing flexibility and allowing for changesin processing methods. Additional wafer processing modules may be addedto the processing tool 10 or replace existing processing modules 19.

[0039] The processing tool 10 of the present invention preferablyincludes a rear closure surface 18 joined with the lateral sides of theprocessing tool 10. As shown in FIG. 1, an air supply 26 may beadvantageously provided intermediate opposing processing modules of theprocessing section 14. The interface section 12, lateral sides of theprocessing section 14, closure surface 18, and air supply 26 preferablyprovide an enclosed work space 11 within the processing tool 10. The airsupply 26 may comprise a duct coupled with a filtered air source (notshown) for providing clean air into the processing tool 10. Morespecifically, the air supply 26 may include a plurality of ventsintermediate the processing modules 19 for introducing clean air intowork space 11.

[0040] Referring to FIG. 16, exhaust ducts 58, 59 may be providedadjacent the frame 65 of a wafer transport unit guide 66 to remove thecirculated clean air and the contaminants therein. Exhaust ducts 58, 59may be coupled with the each of the processing modules 19 for drawingsupplied clean air therethrough. In particular, clean air is supplied tothe workspace 11 of the processing tool 10 via air supply 26. The airmay be drawn adjacent the wafer transport units 62, 64 and into theprocessing modules 19 via a plurality of vents 57 formed within a shelfor process deck thereof by an exhaust fan (not shown) coupled with theoutput of exhaust ducts 58, 59. Each processing module 19 within theprocessing tool 10 may be directly coupled with ducts 58, 59. The airmay be drawn out of the ducts 58, 59 of the processing tool 10 throughthe rear closant surface 18 or through a bottom of surface of theprocessing tool 10. Providing an enclosed work space and controlling theenvironment within the work space greatly reduces the presence ofcontaminants in the processing tool 10.

[0041] Each of the processing modules may be advantageously accessedthrough exterior panels of the respective modules forming the lateralside of the processing tool 10. The lateral sides of the processing tool10 may be adjacent a gray room environment. Gray rooms have fewerprecautions against contamination compared with the clean rooms.Utilizing this configuration reduces plant costs while allowing accessto the processing components and electronics of each wafer module of theprocessing tool 10 which require routine maintenance.

[0042] A user interface 30 may be provided at the outwardly facing frontsurface of the processing tool as shown in FIG. 1. The user interface 30may advantageously be a touch screen cathode ray tube control displayallowing finger contact to the display screen to effect various controlfunctions within the processing tool 10. An additional user interface 30may also be provided at the rear of the processing tool 10 or withinindividual processing modules so that processing tool 10 operation canbe effected from alternate locations about the processing tool 10.Further, a portable user interface 30 may be provided to permit anoperator to move about the processing tool 10 and view the operation ofthe processing components therein. The user interface 30 may be utilizedto teach specified functions and operations to the processing modules 19and semiconductor wafer transport units 62, 64.

[0043] Each module 20, 22, 24 within the processing tool 10 preferablyincludes a window 34 allowing visual inspection of processing tool 10operation from the gray room. Further, vents 37 may be advantageouslyprovided within a top surface of each processing module 20, 22, 24.Processing module electronics are preferably located adjacent the vents37 allowing circulating air to dissipate heat generated by suchelectronics.

[0044] The work space 11 within the interface section 12 and processingsection 14 of an embodiment of the processing tool 10 is shown in detailin FIG. 2.

[0045] The interface section 12 includes two interface modules 38, 39for manipulating wafer cassettes 16 within the processing tool 10. Theinterface modules 38, 39 receive wafer cassettes 16 through the accessports 32, 33 and may store the wafer cassettes 16 for subsequentprocessing of the semiconductor wafers therein. In addition, theinterface modules 38, 39 store the wafer cassettes for removal from theprocessing tool 10 upon completion of the processing of thesemiconductor wafers within the respective wafer cassette 16.

[0046] Each interface module 38, 39 may comprise a wafer cassetteturnstile 40, 41 and a wafer cassette elevator 42, 43. The wafercassette turnstiles 40, 41 generally transpose the wafer cassettes 16from a stable vertical orientation to a horizontal orientation whereaccess to the semiconductor wafers is improved. Each wafer cassetteelevator 42, 43 has a respective wafer cassette support 47, 48 forholding wafer cassettes 16. Each wafer cassette elevator 42, 43 isutilized to position a wafer cassette 16 resting thereon in either atransfer position and extraction position. The operation of the waferinterface modules 38, 39 is described in detail below.

[0047] In a preferred embodiment of the present invention, the firstwafer interface module 38 may function as an input wafer cassetteinterface for receiving unprocessed semiconductor wafers into theprocessing tool 10. The second wafer interface module 39 may function asan output wafer cassette interface for holding processed semiconductorwafers for removal from the processing tool 10. Wafer transport units62, 64 within the processing tool 10 may access wafer cassettes 16 heldby either wafer interface module 38, 39. Such an arrangement facilitatestransferring of semiconductor wafers throughout the processing tool 10.

[0048] A semiconductor wafer conveyor 60 is shown intermediateprocessing modules 20, 22, 24 and interface modules 38, 39 in FIG. 2.The wafer conveyor 60 includes wafer transport units 62, 64 fortransferring individual semiconductor wafers W between each of the waferinterface modules 38, 39 and the wafer processing modules 19.

[0049] Wafer conveyor 60 advantageously includes a transport unit guide66, such as an elongated rail, which defines a plurality of paths 68, 70for the wafer transport units 62, 64 within the processing tool 10. Awafer transport unit 62 on a first path 68 may pass a wafer transportunit 64 positioned on a second path 70 during movement of the transportunits 62, 64 along transport guide 66. The processing tool 10 mayinclude additional wafer transport units to facilitate the transfer ofsemiconductor wafers W between the wafer processing modules 20, 22, 24and wafer interface modules 38, 39.

[0050] More specifically, the second arm extension 88 may support asemiconductor wafer W via vacuum support 89. The appropriate wafertransport unit 62, 64 may approach a wafer support 401 by moving alongtransport unit guide 66. After reaching a proper location along guide66, the first extension 87 and second extension 88 may rotate toapproach the wafer support 401. The second extension 88 is positionedabove the wafer support 401 and subsequently lowered toward engagementfinger assemblies 409 on the wafer support 401.

[0051] The vacuum is removed from vacuum support 89, and fingerassemblies within the processing modules grasp the semiconductor wafer Wpositioned therein. Second extension 88 may be lowered and removed frombeneath the semiconductor wafer held by the wafer engagement fingers.

[0052] Following completion of processing of the semiconductor waferwithin the appropriate processing module 20, 22, 24, a wafer transportunit 62, 64 may retrieve the wafer and either deliver the wafer toanother processing module 20, 22, 24 or return the wafer to a wafercassette 16 for storage or removal from the processing tool 10.

[0053] Each of the wafer transport units 62, 64 may access a wafercassette 16 adjacent the conveyor 60 for retrieving a semiconductorwafer from the wafer cassette 16 or depositing a semiconductor wafertherein. In particular, wafer transport unit 62 is shown withdrawing asemiconductor wafer W from wafer cassette 16 upon elevator 42 in FIG. 2.More specifically, the second extension 88 and vacuum support 89connected therewith may be inserted into a wafer cassette 16 positionedin the extraction position. Second extension 88 and vacuum support 89enter below the lower surface of the bottom semiconductor wafer W heldby wafer cassette 16. A vacuum may be applied via vacuum support 89 oncesupport 89 is positioned below the center of the semiconductor wafer Wbeing removed. The second extension 88, vacuum support 89 andsemiconductor wafer W attached thereto may be slightly raised viatransfer arm elevator 90. Finally, first extension 87 and secondextension 88 may be rotated to remove the semiconductor wafer W from thewafer cassette 16. The wafer transport unit 62, 64 may thereafterdeliver the semiconductor wafer W to a wafer processing module 19 forprocessing.

[0054] Thereafter, wafer transport unit 62 may travel along path 68 to aposition adjacent an appropriate processing module 20, 22, 24 fordepositing the semiconductor wafer upon wafer processing support 401 forprocessing of the semiconductor wafer.

[0055] Interface Module

[0056] Referring to FIG. 3-FIG. 8, the operation of the interface module38 is shown in detail. The following discussion is limited to waferinterface module 38 but is also applicable to wafer interface module 39inasmuch as each interface module 38, 39 may operate in substantiallythe same manner.

[0057] Preferably, the first wafer interface module 38 and the secondwafer interface module 39 may function as a respective semiconductorwafer cassette 16 input module and output module of the processing tool10. Alternately, both modules can function as both input and output.More specifically, wafer cassettes 16 holding unprocessed semiconductorswafers may be brought into the processing tool 10 via port 32 andtemporarily stored within the first wafer interface module 38 until thesemiconductor wafers are to be removed from the wafer cassette 16 forprocessing. Processed semiconductor wafers may be delivered to a wafercassette 16 within the second wafer interface module 39 via wafertransport units 62, 64 for temporary storage and/or removal from theprocessing tool 10.

[0058] The wafer interface modules 38, 39 may be directly accessed byeach of the wafer transport units 62, 64 within the processing tool 10for transferring semiconductor wafers therebetween. Providing aplurality of wafer cassette interface modules 38, 39 accessible by eachwafer transport unit 62, 64 facilitates the transport of semiconductorwafers W throughout the processing tool 10 according to the presentinvention.

[0059] Each wafer interface module 38, 39 preferably includes a wafercassette turnstile 40 and a wafer cassette elevator 42 adjacent thereto.The access ports 32, 33 are adjacent the respective wafer cassetteturnstiles 40, 41. Wafer cassettes 16 may be brought into the processingtool 10 or removed therefrom via ports 32, 33.

[0060] Wafer cassettes 16 are preferably placed in a vertical positiononto cassette trays 50 prior to delivery into the processing tool 10.Cassette trays 50 are shown in detail in FIG. 9. The vertical positionof wafer cassettes 16 and the semiconductor wafers therein provides asecure orientation to maintain the semiconductor wafers within the wafercassette 16 for transportation.

[0061] Each wafer cassette turnstile 40, 41 preferably includes twosaddles 45, 46 each configured to hold a wafer cassette 16. Providingtwo saddles 45, 46 enables two wafer cassettes 16 to be placed into theprocessing tool 10 or removed therefrom during a single opening of arespective access door 35, 36 thereby minimizing exposure of theworkspace 11 within the processing tool 10 to the clean roomenvironment.

[0062] Each saddle 45, 46 includes two forks engageable with thecassette tray 50. Saddles 45, 46 are powered by motors within the wafercassette turnstile shaft 49 to position the wafer cassette 16 in ahorizontal or vertical orientation. The wafer cassettes 16 andsemiconductor wafers therein are preferably vertically oriented forpassage through the access ports 32, 33 and horizontally oriented in atransfer or extraction position to provide access of the wafers thereinto the wafer transport units 62, 64.

[0063] The wafer cassette 16 held by wafer cassette turnstile 40 in FIG.3, also referred to as wafer cassette 15, is in a hold position (alsoreferred to herein as a load position). The semiconductor wafers withina wafer cassette 16 in the hold position may be stored for subsequentprocessing. Alternatively, the semiconductor wafers within a wafercassette 16 in the hold position may be stored for subsequent removalfrom the processing tool 10 through an access port 32, 33.

[0064] Referring to FIG. 3, the wafer cassette 16 supported by the wafercassette elevator 42, also referred to as wafer cassette 17, is in anextraction or exchange position. Semiconductor wafers may either beremoved from or placed into a wafer cassette 16 positioned in theextraction position via a wafer transport unit 62, 64.

[0065] The wafer cassette turnstile 41 and wafer cassette elevator 42may exchange wafer cassettes 15, 17 to transfer a wafer cassette 17having processed semiconductor wafers therein from the extractionposition to the hold position for removal from the processing tool 10.Additionally, such an exchange may transfer a wafer cassette 15 havingunprocessed semiconductor wafers therein from the hold position to theextraction position providing wafer transport units 62, 64 with accessto the semiconductor wafer therein.

[0066] The exchange of wafer cassettes 15, 17 is described withreference to FIG. 4-FIG. 8. Specifically, saddle 46 is positioned belowa powered shaft 44 of wafer cassette elevator 42. Shaft 44 is coupledwith a powered wafer cassette support 47 for holding a wafer cassette16. Shaft 44 and wafer cassette support 47 attached thereto are loweredas shown in FIG. 4 and shaft 44 passes between the forks of saddle 46.

[0067] Referring to FIG. 5, a motor within shaft 44 rotates wafercassette support 47 about an axis through shaft 44 providing the wafercassette 17 thereon in an opposing relation to the wafer cassette 15held by wafer cassette turnstile 40. Both saddles 45, 46 of wafercassette turnstile 40 are subsequently tilted into a horizontalorientation as shown in FIG. 6. The shaft 44 of wafer cassette elevator42 is next lowered and wafer cassette 17 is brought into engagement withsaddle 46 as depicted in FIG. 7. The shaft 44 and wafer cassette support47 are lowered an additional amount to clear rotation of wafer cassettes16. Referring to FIG. 8, wafer cassette turnstile 40 rotates 180 degreesto transpose wafer cassettes 15, 17.

[0068] Wafer cassette 17 having processed semiconductor wafers thereinis now accessible via port 32 for removal from the processing tool 10.Wafer cassette 15 having unprocessed semiconductors therein is nowpositioned for engagement with wafer cassette support 47. The transferprocess steps shown in FIG. 3-FIG. 8 may be reversed to elevate thewafer cassette 15 into the extraction position providing access of thesemiconductor wafers to wafer transport units 62, 64.

[0069]FIG. 10 illustrates one manner in which the apparatus 10 may bemodularized. As illustrated, the apparatus 10 is comprised of aninput/output assembly 800, left and right processing modules 805, 810,wafer conveyor system 60, top exhaust assembly 820, and end panel 825.As illustrated, left and right processing modules 805 and 810 may besecured to one another about the wafer conveying system 60 to form aprocessing chamber having an inlet and 830 and an outlet 835. Aplurality of these processing modules may thus be secured in anend-to-end configuration to thereby provide an extended processingchamber capable of performing a substantially larger number of processeson each wafer or, in the alternative, process a larger number of wafersconcurrently. In such instances, the wafer conveying system 60 of oneapparatus 10 is programmed to cooperate with the wafer conveying system60 of one or more prior or subsequent conveying systems 60.

[0070]FIG. 11 illustrates one manner of arranging processing headswithin the apparatus 10. In this embodiment, the left hand processingmodule 805 is comprised of three processing heads that are dedicated torinsing and drying each wafer after electrochemical deposition and twoprocessing heads for performing wetting of the wafers prior toelectrochemical deposition. Generically, the left hand processing module805 constitutes a support module having processing heads used inpre-processing and post-processing of the wafers with respect toelectrochemical copper deposition. The right-hand module 810 genericallyconstitutes a plating module and includes five reactor heads dedicatedto electrochemical copper deposition. In the embodiment of FIG. 11, awafer alignment station 850 is provided to ensure thickness properorientation of each wafer as it is processed in the apparatus. Waferalignment may be based upon sensing of registration marks or the like oneach wafer.

[0071]FIGS. 12 and 13 illustrate embodiments of the left and right handprocessing modules 805 and 810, respectively. In these figures, theexterior portions of the respective housing have been removed therebyexposing various system components. Preferably, electronic componentssuch as power supplies, controllers, etc., are disposed in the upperportion of each of the processing modules 805 and 810, while movingcomponents and the like are disposed in a lower portion of each of theprocessing modules.

[0072]FIG. 14 is a perspective view of the input module 800 with itspanels removed as viewed from the interior of apparatus 10. FIG. 15provides a similar view of the input module 800 with respect to theexterior of apparatus 10. In the illustrated embodiment, the waferalignment station 850 and a wafer alignment controller 860 are providedin the input module 800. A robot controller 865 used to control thewafer conveying system 60 is also disposed therein. To keep track of thewafers as they are processed, the input module 800 is provided with oneor more wafer mapping sensors 870 that sense the wafers present in eachcassette. Other components in the input module 800 include the systemcontrol computer 875 and a four-axis controller 880. The system controlcomputer 875 is generally responsible for coordinating all operations ofthe apparatus 10.

[0073] Semiconductor Wafer Conveyor

[0074] The processing tool 10 includes a semiconductor wafer conveyor 60for transporting semiconductor wafers throughout the processing tool 10.Preferably, semiconductor wafer conveyor 60 may access each wafercassette interface module 38, 39 and each wafer processing module 19within processing tool 10 for transferring semiconductor waferstherebetween. This includes processing modules from either side.

[0075] One embodiment of the wafer conveyor system 60 is depicted inFIG. 16. The wafer conveyor 60 generally includes a wafer transport unitguide 66 which preferably comprises an elongated spine or rail mountedto frame 65. Alternatively, transport unit guide 66 may be formed as atrack or any other configuration for guiding the wafer transport units62, 64 thereon. The length of wafer conveyor 60 may be varied and isconfigured to permit access of the wafer transport units 62, 64 to eachinterface module 38, 39 and processing modules 20, 22, 24.

[0076] Wafer transport unit guide 66 defines the paths of movement 68,70 of wafer transport units 62, 64 coupled therewith. Referring to FIG.16, a spine of transport unit guide 66 includes guide rails 63, 64mounted on opposite sides thereof. Each semiconductor wafer transportunit 62, 64 preferably engages a respective guide rail 63, 64. Eachguide rail can mount one or more transport units 62, 64. Extensions 69,75 may be fixed to opposing sides of guide 66 for providing stability ofthe transport units 62, 64 thereagainst and to protect guide 66 fromwear. Each wafer transport unit 62, 64 includes a roller 77 configuredto ride along a respective extension 69, 75 of guide 66.

[0077] It is to be understood that wafer conveyor 60 may be formed inalternate configurations dependent upon the arrangement of interfacemodules 38, 39 and processing modules 20, 22, 24 within the processingtool 10. Ducts 58, 59 are preferably in fluid communication withextensions from each wafer processing module 19 and an exhaust fan forremoving circulated air from the workspace 11 of the processing tool 10.

[0078] Each wafer transport unit 62, 64 is powered along the respectivepath 68, 70 by a suitable driver. More specifically, drive operators 71,74 are mounted to respective sides of transport unit guide 66 to providecontrollable axial movement of wafer transport units 62, 64 along thetransport unit guide 66.

[0079] The drive operators 71, 74 may be linear magnetic motors forproviding precise positioning of wafer transport units 62, 64 alongguide 66. In particular, drive operators 71, 74 are preferably linearbrushless direct current motors. Such preferred driver operators 71, 74utilize a series of angled magnetic segments which magnetically interactwith a respective electromagnet 79 mounted on the wafer transport units62, 64 to propel the units along the transport unit guide 66.

[0080] Cable guards 72, 73 may be connected to respective wafertransport units 62, 64 and frame 65 for protecting communication andpower cables therein. Cable guards 72, 73 may comprise a plurality ofinterconnected segments to permit a full range of motion of wafertransport units 62, 64 along transport unit guide 66.

[0081] As shown in FIG. 17, a first wafer transport unit 62 is coupledwith a first side of the spine of guide 66. Each wafer transport unit62, 64 includes a linear bearing 76 for engagement with linear guiderails 63, 64. Further, the wafer transport units 62, 64 each preferablyinclude a horizontal roller 77 for engaging a extension 69 formed uponthe spine of the guide 66 and providing stability.

[0082]FIG. 17 additionally shows an electromagnet 79 of the first wafertransport unit 62 mounted in a position to magnetically interact withdrive actuator 71. Drive actuator 71 and electromagnet 79 provide axialmovement and directional control of the wafer transport units 62, 64along the transport unit guide 66.

[0083] Semiconductor Wafer Transport Units

[0084] Preferred embodiments of the semiconductor wafer transport units62, 64 of the wafer conveyor 60 are described with reference to FIG. 18and FIG. 19.

[0085] In general, each wafer transport unit 62, 64 includes a movablecarriage or tram 84 coupled to a respective side of the transport unitguide 66, a wafer transfer arm assembly 86 movably connected to the tram84 for supporting a semiconductor wafer W, and a wafer transfer armelevator 90 for adjusting the elevation of the transfer arm assembly 86relative to tram 84.

[0086] Referring to FIG. 18, a cover 85 surrounds the portion of tram 84facing away from the transport unit guide 66. Tram 84 includes linearbearings 76 for engagement with respective guide rails 63, 64 mounted totransport unit guide 66. Linear bearings 76 maintain the tram 84 in afixed relation with the transport unit guide 66 and permit axialmovement of the tram 84 therealong. A roller 77 engages a respectiveextension 69 for preventing rotation of tram 84 about guide rail 63, 64and providing stability of wafer transport unit 62. The electromagnet 79is also shown connected with the tram 84 in such a position tomagnetically interact with a respective transport unit 62, 64 driveactuator 71, 74.

[0087] A wafer transfer arm assembly 86 extends above the top of tram84. The wafer transfer arm assembly 86 may include a first arm extension87 coupled at a first end thereof with a shaft 83. A second armextension 88 may be advantageously coupled with a second end of thefirst extension 87. The first arm extension 87 may rotate 360 degreesabout shaft 83 and second arm extension 88 may rotate 360 degrees aboutaxis 82 passing through a shaft connecting first and second armextensions 87, 88.

[0088] Second extension 88 preferably includes a wafer support 89 at adistal end thereof for supporting a semiconductor wafer W during thetransporting thereof along wafer conveyor 60. The transfer arm assembly86 preferably includes a chamber coupled with the wafer support 89 forapplying a vacuum thereto and holding a semiconductor wafer W thereon.

[0089] Providing adjustable elevation of transfer arm assembly 86,rotation of first arm extension 87 about the axis of shaft 83, androtation of second extension 88 about axis 82 allows the transfer arm 86to access each semiconductor wafer holder 810 of all processing modules19 and each of the wafer cassettes 16 held by interface modules 38, 39within the processing tool 10. Such access permits the semiconductorwafer transport units 62, 64 to transfer semiconductor waferstherebetween.

[0090] The cover 85 has been removed from the wafer transport unit shownin FIG. 19 to reveal a wafer transfer arm elevator 90 coupled with tram84 and transfer arm assembly 86. Transfer arm elevator 90 adjusts thevertical position of the transfer arm assembly 86 relative to the tram84 during the steps of transferring a semiconductor wafer between thewafer support 89 and one of a wafer holder 810 and the wafer cassette16.

[0091] The path position of the tram 84 of each wafer transport unit 62,64 along the transport unit guide 66 is precisely controlled using apositional indicating array, such as a CCD array 91 of FIG. 19. In oneembodiment of the processing tool 10, each semiconductor wafer holder810 within a processing module 19 has a corresponding light or otherbeam emitter 81 mounted on a surface of the processing module 19 asshown in FIG. 2 for directing a beam of light toward the transport unitguide 66. The light emitter 81 may present a continuous beam oralternatively may be configured to generate the beam as a wafertransport unit 62, 64 approaches the respective wafer holder 810.

[0092] The transfer arm assembly 86 includes an CCD array 91 positionedto receive the laser beam generated by light emitter 81. A positionindicating array 91 on shaft 83 detects the presence of the light beamto determine the location of tram 84 along transport unit guide 66. Thepositional accuracy of the wafer transport unit position indicator ispreferably in the range less than 0.003 inch (approximately less than0.1 millimeter).

[0093] A second embodiment of a wafer transport unit 562 b is shown inFIGS. 20-25 and is similarly provided with a movable carriage or tram584 coupled to a respective side of the transport unit guide 66, a wafertransfer arm assembly 586 movably connected to the tram 584 forsupporting a semiconductor wafer W, and a wafer transfer arm elevator590 for adjusting the elevation of the transfer arm assembly 586relative to tram 584. A cover 585 surrounds a portion of tram 584. Tram584 includes linear bearings 576 for engagement with respective guiderails 63, 64 mounted to transport unit guide 66. Linear bearings 576maintain the tram 584 in a fixed relation with the transport unit guide66 and permit axial movement of the tram 584 therealong. Theelectromagnet 579 magnetically interacts with the guide 66 to driveactuator 71, 74.

[0094] A wafer transfer arm assembly 586 extends above the top of tram584. The wafer transfer arm assembly 586 includes a first arm extension587 coupled at a first end thereof with a shaft 583. A second armextension 588, having a wafer support 589 for supporting thesemiconductor wafer W, may be advantageously coupled with a second endof the first extension 587. The first arm extension 587 may rotate 360degrees about shaft 583 and second arm extension 588 may rotate 360degrees about axis 582 passing through a shaft connecting first andsecond arm extensions 587, 588.

[0095] As with the first embodiment, providing adjustable elevation oftransfer arm assembly 586, rotation of first arm extension 587 about theaxis of shaft 583, and rotation of second extension 588 about axis 582permits the semiconductor wafer transport units 562 a, 562 b to transfersemiconductor wafers therebetween.

[0096] As shown in FIG. 21, cover 585 has been removed from the wafertransport unit 562 b, revealing a wafer transfer arm elevator 590coupled with tram 584 and transfer arm assembly 586. Transfer armelevator 590 adjusts the vertical position of the transfer arm assembly586 relative to the tram 584 during a transfer of a semiconductor wafer.

[0097] In the second embodiment of the wafer transport units 562 a, 562b, a fiber optic communication path, such as a fiber optic filament,replaces wires 72, 73 to the wafer transport units through adigital-to-analog converter board 540 on each of the wafer transportunits 562 a, 562 b. The use of fiber optics as opposed to wire harnesseslowers the inertial mass of the transport units 562 a, 562 b andimproves reliability. One manner of implementing circuitry for such afiber optic communication link and corresponding control at thetransport units is set forth in the schematics of FIGS. 34-64.Preferably, such communications take place between the transfer unit andthe system controller 875.

[0098] The path and operational position of the tram 584 of each wafertransport unit 562 a, 562 b along the transport unit guide 66 isprecisely controlled using a combination of encoders to provide positioninformation on the position of the tram 584, transfer arm assembly 586and second extension 588 in three-axis space. An absolute encoder, theposition of which is shown at 591, is located in the elevator 590. Anabsolute encoder, TPOW, is shown at 592, located in the base motor 593of the shaft 583. An absolute encoder, TPOW, is shown at 594, located inthe shaft 583. Wrist absolute encoder, the position of which is shown at595, is located at the distal end of transfer arm assembly 586. An elbowabsolute encoder, TPOWISA, 597 is provided at the base of the shaft 583.Lift absolute encoder 596 is located along the base motor 593. A linearencoder 598, head rail encoder 599 and track CDD array absolute encoder541 are located on the base plate 203 of the base of tram 584, thelatter located for sensing the beam emitter 81 mounted on a surface ofthe processing module 19 as shown in FIG. 2 and discussed above. Theforegoing allows precise and reliable positional accuracy.

[0099] Mounting of the wafer transport units is shown in FIG. 22. Asillustrated, a wafer conveyor 560 includes a wafer transport unit guide566 which comprises an elongated spine or rail mounted to frame 565.Wafer transport unit guide 566 defines the paths of movement 568, 570 ofwafer transport units 544 a, 544 b. A spine of transport unit guide 566includes upper guide rails 563 a, 564 a and lower guide rails 563 b, 564b mounted on opposite sides thereof. Each semiconductor wafer transportunit 544 a, 544 b preferably engages each of the respective upper guiderails 563 a, 564 b and lower guide rails 563 b, 564 b. Each of the pairof upper and lower guide rails can mount one or more transport units 544a, 544 b.

[0100] Each wafer transport unit 544 a, 544 b is also powered along therespective path 568, 570 by drive operators 571, 574 mounted torespective sides of transport unit guide 66 to provide controllableaxial movement of wafer transport units 544 a, 544 b along the transportunit guide 566. The drive operators 571, 574 may be linear magneticmotors for providing precise positioning of wafer transport units 544 a,544 b along guide 566, and are again preferably linear brushless directcurrent motors utilizing a series of angled magnetic segments whichmagnetically interact with a respective electromagnet 579 mounted oneach of the wafer transport units 544 a, 544 b to propel the units alongthe transport unit guide 566.

[0101] Fiber optic cable guards 572, 573 provide communication with therespective wafer transport units 544 a, 544 b and protect fiber opticcables located therein. Cable guards 572, 573 may comprise a pluralityof interconnected segments to permit a full range of motion of wafertransport units 544 a, 544 b along transport unit guide 566.

[0102] As shown in FIG. 22, wafer transport units 544 a, 544 b arecoupled along each side of the spine of guide 566. Each wafer transportunit 544 a, 544 b includes an upper linear bearing 576 a for engagementwith upper linear guide rails 563 a, 564 a, respectively. Further, eachwafer transport units 544 a, 544 b includes a lower linear bearing 576 bengaging the lower linear guide rails 563 b, 564 b, providing stabilityand more equal distribution of the weight loads upon the rails.

[0103] With reference to FIGS. 22-24, the upper and lower linear bearing576 a, 576 b also provides a means by which the vertical axis of thewafer transfer arm assembly 586 extending above the top of tram 584 maybe adjusted. It is important that the transfer arm assembly 586 rotatein a plane as close as possible to the absolute horizontal plane duringthe transfer of wafers within the processing tool 10. To this end, thelower elbow housing 210 of the transfer arm assembly, shown in FIG. 25,mounted to the base plate 203 of the transport unit 544 a is providedwith a tilt adjustment.

[0104] The lower elbow housing 210 is mounted to a base plate 211, asseen in FIGS. 21, 23 and 24 through upper mounting screws 212 and lowermounting screws 214. The base plate 211 is in turn fastened to theelevator motor 590 to raise or lower the transfer arm assembly 586,better seen in FIG. 25. As seen in FIG. 26, positioned laterally betweenthe upper mounting screws 212 are embossed pivots 216 on the base plate211 that engage a corresponding, yet slightly smaller, lateral groove218 on the lower elbow housing 210. The pivots 216 are preferably sized,relative the lateral groove 218 to provide a clearance between the baseplate 211 and the lower elbow housing 210 so that about 0.95 degrees oftilt is available between the two. In combination with one or moreleveling screws 220 and the upper and lower mounting screws 212, 214,the angular orientation of the lower elbow housing 210, and the attachedtransfer arm assembly 586, can be adjusted and fixed to provide rotationof the transfer arm assembly 586 as close as possible within theabsolute horizontal plane during the transfer of wafers within theprocessing tool 10.

[0105] Also, compliant attachment of the lower linear bearing guides 576b is important to smooth operation of the wafer transport unit 544 a,544 b along the guide 566. Providing such compliant attachment,preferably allowing 0.100 inch of float, at the lower gearing guides 576b is obtained by use of a compliant fastening technique. A float pin 221is positioned about mounting screw 222, with an O-ring 223, preferablyVITON, positioned about the float pin. When installed within shoulderedcounterbore 224 of the base plate 203 into tapped hole 227 of lowerbearing guide 576 b, as shown in FIG. 28, the screw 222 bears against aflange 225 of the float pin 221, which in turn bears against the O-ring223. The O-ring 223 then bears against the shoulder 226 of thecounterbore. However, even when the screw 222 is tightened, relativemotion is allowed between the lower bearing guide 576 b and the baseplate 203 to facilitate smooth motion over the entire guide 566.

[0106] Control System

[0107] Referring to FIG. 26, there is shown one embodiment of thecontrol system 100 of the semiconductor wafer processing tool 10. Asillustrated, the control system 100 generally includes at least onegrand master controller 101 for controlling and/or monitoring theoverall function of the processing tool 10.

[0108] The control system 100 is preferably arranged in a hierarchialconfiguration. The grand master controller 101 includes a processorelectrically coupled with a plurality of subsystem control units asshown in FIG. 26. The control subsystems preferably control and monitorthe operation of components of the corresponding apparatus (i.e., waferconveyor 60, processing modules 20, 22, 24, interface modules 38, 39,etc.). The control subsystems are preferably configured to receiveinstructional commands or operation instructions such as software codefrom a respective grand master control 101, 102. The control subsystems110, 113-119 preferably provide process and status information torespective grand master controllers 101, 102.

[0109] More specifically, the grand master control 101 is coupled withan interface module control 110 which may control each of thesemiconductor wafer interface modules 38, 39. Further, grand mastercontrol 101 is coupled with a conveyor control 113 for controllingoperations of the wafer conveyor 60 and a plurality of processing modulecontrols 114, 115 corresponding to semiconductor wafer processingmodules 20, 22 within the processing tool 10. The control system 100 ofthe processing tool 10 according to the present disclosure may includeadditional grand master controllers 102 as shown in FIG. 26 formonitoring or operating additional subsystems, such as additional waferprocessing modules via additional processing module control 119. Fourcontrol subsystems may be preferably coupled with each grand mastercontroller 101, 102. The grand master controllers 101, 102 arepreferably coupled together and each may transfer process data to theother.

[0110] Each grand master controller 101, 102 receives and transmits datato the respective modular control subsystems 110-119. In a preferredembodiment of the control system 100, a bidirectional memory mappeddevice is provided intermediate the grand master controller and eachmodular subsystem connected thereto. In particular, memory mappeddevices 160, 161, 162 are provided intermediate the grand mastercontroller 101 and master controllers 130, 131, 132 within respectiveinterface module control 110, wafer conveyor control 113 and processingmodule control 114.

[0111] Each memory mapped device 150, 160-162 within the control system100 is preferably a dual port RAM provided by Cypress for asynchronously storing data. In particular, grand master controller 101may write data to a memory location corresponding to master controller130 and master controller 130 may simultaneously read the data.Alternatively, grand master controller 101 may read data from mappedmemory device being written by the master controller 130. Utilizingmemory mapped devices 160-161 provides data transfer at processorspeeds. Memory mapped device 150 is preferably provided intermediateuser interface 30 and the grand master controllers 101, 102 fortransferring data therebetween.

[0112] A user interface 30 is preferably coupled with each of the grandmaster controllers 101, 102. The user interface 30 may be advantageouslymounted on the exterior of the processing tool 10 or at a remotelocation to provide an operator with processing and status informationof the processing tool 10. Additionally, an operator may input controlsequences and processing directives for the processing tool 10 via userinterface 30. The user interface 30 is preferably supported by a generalpurpose computer within the processing tool 10. The general purposecomputer preferably includes a 486 100 MHz processor, but otherprocessors may be utilized.

[0113] Each modular control subsystem, including interface modulecontrol 110, wafer conveyor control 113 and each processing modulecontrol 114-119, is preferably configured in a master/slave arrangement.The modular control subsystems 110, 113-119 are preferably housed withinthe respective module such as wafer interface module 38, 39, waferconveyor 60, or each of the processing modules 20, 22, 24. The grandmaster controller 101 and corresponding master controllers 130, 131, 132coupled therewith are preferably embodied on a printed circuit board orISA board mounted within the general purpose computer supporting userinterface 30. Each grand master controller 101, 102 preferably includesa 68EC000 processor provided by Motorola and each master controller 130and slave controller within control system 100 preferably includes a80251 processor provided by Intel.

[0114] Each master controller 130, 131, 132 is coupled with itsrespective slave controllers via a data link 126, 127, 129 as shown inFIG. 27-FIG. 30. Each data link 126, 127, 129 preferably comprises anoptical data medium such as Optilink provided by Hewlett Packard.However, data links 126, 127, 129 may comprise alternate data transfermedia.

[0115] Referring to FIG. 27, the master/slave control subsystem for theinterface module control 110 is illustrated. Each master and relatedslave configuration preferably corresponds to a single module (i.e.,interface, conveyor, processing) within the processing tool 10. However,one master may control or monitor a plurality of modules. Themaster/slave configuration depicted in FIG. 27 and corresponding to theinterface module control 110 may additionally apply to the other modularcontrol subsystems 113, 114, 115.

[0116] The grand master controller 101 is connected via memory mappeddevice 160 to a master controller 130 within the corresponding interfacemodule control 110. The master controller 130 is coupled with aplurality of slave controllers 140, 141, 142. Sixteen slave controllersmay be preferably coupled with a single master controller 130-132 andeach slave controller may be configured to control and monitor a singlemotor or process component, or a plurality of motors and processcomponents.

[0117] The control system 100 of the processing tool 10 preferablyutilizes flash memory. More specifically, the operation instructions orprogram code for operating each master controller 130-132 and slavecontroller 140-147 within the control system 100 may be advantageouslystored within the memory of the corresponding grand master controller101, 102. Upon powering up, the grand master controller 101, 102 maypoll the corresponding master controllers 130-132 and download theappropriate operation instruction program to operate each mastercontroller 130-132. Similarly, each master controller 130-132 may pollrespective slave controllers 140-147 for identification. Thereafter, themaster controller 130-132 may initiate downloading of the appropriateprogram from the grand master controller 101, 102 to the respectiveslave controller 140-147 via the master controller 130-132.

[0118] Each slave controller may be configured to control and monitor asingle motor or a plurality of motors within a corresponding processingmodule 19, interface module 38, 39 and wafer conveyor 60. In addition,each slave controller 140-147 may be configured to monitor and controlprocess components 184 within a respective module 19. Any one slavecontroller, such as slave controller 145 shown in FIG. 36, may beconfigured to control and/or monitor servo motors and process components184.

[0119] Each slave controller includes a slave processor which is coupledwith a plurality of port interfaces. Each port interface may be utilizedfor control and/or monitoring of servo motors and process components184. For example, a port may be coupled with a servo controller card 176which is configured to operate a wafer transfer unit 62 a, 62 b. Theslave processor 171 may operate the wafer transfer unit 62 a, 62 b viathe port and servo controller 176. More specifically, the slaveprocessor 171 may operate servo motors within the wafer transfer unit 62a, 62 b and monitor the state of the motor through the servo controller176.

[0120] Alternatively, different slave controllers 140, 141 may operatedifferent components within a single processing tool device, such asinterface module 38. More specifically, the interface module control 110and components of the interface module 38 are depicted in FIG. 32. Slavecontroller 140 may operate turnstile motor 185 and monitor the positionof the turnstile 40 via incremental turnstile encoder 190. Slavecontroller 140 is preferably coupled with the turnstile motor 185 andturnstile encoder 190 via a servo control card (shown in FIG. 35). Slavecontroller 141 may operate and monitor saddle 45 of the turnstile 40 bycontrolling saddle motor 186 and monitoring saddle encoder 191 via aservo control card.

[0121] A port of a slave processor may be coupled with an interfacecontroller card 180 for controlling and monitoring process componentswithin a respective processing module 19. For example, a flow sensor 657may provide flow information of the delivery of processing fluid to aprocessing bowl within the module. The interface controller 180 isconfigured to translate the data provided by the flow sensors 657 orother process components into a form which may be analyzed by thecorresponding slave processor 172. Further, the interface controller 180may operate a process component, such as a flow controller 658,responsive to commands from the corresponding slave processor 172.

[0122] One slave controller 140-147 may contain one or more servocontroller and one or more interface controller coupled with respectiveports of the slave processor 170-172 for permitting control and monitorcapabilities of various component motors and processing components froma single slave controller.

[0123] Alternatively, a servo controller and interface controller mayeach contain an onboard processor for improving the speed of processingand operation. Data provided by an encoder or process component to theservo controller or interface controller may be immediately processed bythe on board processor which may also control a respective servo motoror processing component responsive to the data. In such a configuration,the slave processor may transfer the data from the interface processoror servo controller processor to the respective master controller andgrand master controller.

[0124] Conveyor Control Subsystem

[0125] The conveyor control subsystem 113 for controlling and monitoringthe operation of the wafer conveyor 60 and the wafer transport units 62a, 62 b or 562 a, 562 b or 544 a, 544 b therein is shown in FIG. 29. Ingeneral, a slave controller 143 of conveyor control 113 is coupled withdrive actuator 71 for controllably moving and monitoring a wafertransport unit 62 a along the guide 66. Further, slave controller 143may operate transfer arm assembly 86 of the wafer transport unit 62 a or562 a or 544 a and the transferring of semiconductor wafers thereby.Similarly, slave controller 144 may be configured to operate wafertransport unit 62 b or 562 b or 544 b and drive actuator 74.

[0126] The interfacing of slave controller 143 and light detector 91,drive actuator 71, linear encoder 196 and wafer transport unit 62 a isshown in detail in FIG. 36. The slave processor 171 of slave controller143 is preferably coupled with a servo controller 176. Slave processor171 may control the linear position of wafer transport unit 62 a byoperating drive actuator 71 via servo controller 176. Light detector 91may provide linear position information of the wafer transport unit 62 aalong guide 66. Additionally, a linear encoder 196 may also be utilizedfor precisely monitoring the position of wafer transport unit 62 alongguide 66.

[0127] The conveyor slave processor 171 may also control and monitor theoperation of the transfer arm assembly 86 of the corresponding wafertransport unit 62 a. Specifically, the conveyor processor 171 may becoupled with a transfer arm motor 194 within shaft 83 for controllablyrotating the first and second arm extensions 87, 88. An incrementaltransfer arm rotation encoder 197 may be provided within the shaft 83 ofeach wafer transport unit 62 a for monitoring the rotation of transferarm assembly 86 and providing rotation data thereof to servo controller176 and slave processor 171.

[0128] Slave controller 143 may be advantageously coupled with transferarm elevation motor 195 within elevator 90 for controlling theelevational position of the transfer arm assembly 86. An incrementaltransfer arm elevation encoder 198 may be provided within the transferarm elevator assembly 90 for monitoring the elevation of the transferarm assembly 86.

[0129] In addition, conveyor slave controller 143 may be coupled with anair supply control valve actuator (not shown) via an interfacecontroller for controlling a vacuum within wafer support 89 forselectively supporting a semiconductor wafer thereon.

[0130] Absolute encoders 199 may be provided within the wafer conveyor60, interface modules 38, 39 and processing modules 19 to detect extremeconditions of operation and protect servo motors therein. For example,absolute encoder 199 may detect a condition where the transfer armassembly 86 has reached a maximum height and absolute encoder 199 mayturn off elevator 90 to protect transfer arm elevator motor 195.

[0131] A similar approach may be used for the fiber optic signalcommunication system of the second and third embodiments of the wafertransfer units 562 a, 562 b and 544 a, 544 b, respectively. Particular,encoder 591 located in the elevator 590, encoder 592 located in the basemotor 593 of the shaft 583, encoder 594 located in the shaft 583, wristabsolute encoder 595 located at the distal end of transfer arm assembly586 and elbow absolute encoder 597 located at the base of the shaft 583provide the rotational input of rotational encoder 193 of FIG. 35.Likewise, lift absolute encoder 596 located along the base motor 593,linear encoder 598, head rail encoder 599 and track CDD array absoluteencoder 541 provide inputs for the lift encoder 192 and absolute encoder199 of FIG. 35, respectively.

[0132] Processing Module Control

[0133] The control system 100 preferably includes a processing modulecontrol subsystem 114-116 corresponding to each wafer processing module20, 22, 24 within the processing tool 10 according to the presentdisclosure. The control system 100 may also include additionalprocessing module control subsystem 119 for controlling and/ormonitoring additional wafer processing modules 19.

[0134] Respective processing module controls 114, 115, 116 may controland monitor the transferring of semiconductor wafers W between acorresponding wafer holder 810 and wafer transport unit 62 a, 62 b or562 a, 562 b or 544 a, 544 b. Further, processing module controls 114,115, 116 may advantageously control and/or monitor the processing of thesemiconductor wafers W within each processing module 20, 22, 24.

[0135] Referring to FIG. 30, a single slave controller 147 may operate aplurality of wafer holders 401 c-401 e within a processing module 20.Alternatively, a single slave controller 145, 146 may operate andmonitor a single respective wafer holder 401 a, 401 b. An additionalslave controller 148 may be utilized to operate and monitor all processcomponents 184 (i.e., flow sensors, valve actuators, heaters,temperature sensors) within a single processing module 19. Further, asshown in FIG. 37, a single slave controller 145 may operate and monitora wafer holder 410 and process components 184.

[0136] In addition, a single slave controller 145-148 may be configuredto operate and monitor one or more wafer holder 401 and processingcomponents 184. The interfacing of a slave controller 145 to both awafer holder 401 and process components are shown in the control systemembodiment in FIG. 37. In particular, a servo controller 177 andinterface controller 180 may be coupled with respective ports connectedto slave processor 172 of slave controller 145. Slave processor 172 mayoperate and monitor a plurality of wafer holder components via servocontroller 177. In particular, slave processor 172 may operate liftmotor 427 for raising operator arm 407 about lift drive shaft 456. Anincremental lift motion encoder 455 may be provided within a waferholder 401 to provide rotational information of lift arm 407 to therespective slave processor 172 or a processor within servo controller177. Slave processor 172 may also control a rotate motor 428 withinwafer holder 401 for rotating a processing head 406 about shafts 429,430 between a process position and a semiconductor wafer transferposition. Incremental rotate encoder 435 may provide rotationalinformation regarding the processing head 406 to the corresponding slaveprocessor 172.

[0137] Spin motor 480 may also be controlled by a processor within servocontroller 177 or slave processor 172 for rotating the wafer holder 478during processing of a semiconductor wafer W held thereby. Anincremental spin encoder 498 is preferably provided to monitor the rateof revolutions of the wafer holder 478 and supply the rate informationto the slave processor 172.

[0138] Plating module control 114 advantageously operates the fingertips414 of the wafer holder 478 for grasping or releasing a semiconductorwafer. In particular, slave processor 172 may operate a valve viapneumatic valve actuator 201 for supplying air to pneumatic piston 502for actuating fingertips 414 for grasping a semiconductor wafer. Theslave controller 145 within the plating module control 114 maythereafter operate the valve actuator 201 to remove the air supplythereby disengaging the fingertips 414 from the semiconductor wafer.Slave processor 172 may also control the application of electricalcurrent through the finger assembly 824 during the processing of asemiconductor wafer by operating relay 202.

[0139] The processing module controls 114, 115, 116 preferably operateand monitor the processing of semiconductor wafers within thecorresponding wafer processing modules 20, 22, 24 via instrumentation orprocess components 184.

[0140] Referring to FIG. 33, the control operation for the platingprocessing module 20 is described. Generally, slave processor 172monitors and/or controls process components 184 via interface controller180. Slave processor 172 within the plating module control 114 operatespump 605 to draw processing solution from the process fluid reservoir604 to the pump discharge filter 607. The processing fluid passesthrough the filter, into supply manifold 652 and is delivered via bowlsupply lines to a plurality of processing plating bowls wherein thesemiconductor wafers are processed. Each bowl supply line preferablyincludes a flow sensor 657 coupled with the plating processing modulecontrol 114 for providing flow information of the processing fluidthereto. Responsive to the flow information, the slave processor 172 mayoperate an actuator of flow controller 658 within each bowl supply lineto control the flow of processing fluid therethrough. Slave processor172 may also monitor and control a back pressure regulator 656 formaintaining a predetermined pressure level within the supply manifold652. The pressure regulator 656 may provide pressure information to theslave processor 172 within the plating processing control module 114.

[0141] Similarly, processing module control subsystems 115, 116 may beconfigured to control the processing of semiconductor wafers within thecorresponding prewet module 22 and resist module 24.

[0142] Interface Module Control

[0143] Each interface module control subsystem 110 preferably controlsand monitors the operation of wafer interface modules 38, 39. Morespecifically, interface module control 110 controls and monitors theoperation of the wafer cassette turnstiles 40, 41 and elevators 42, 43of respective semiconductor wafer interface modules 38, 39 to exchangewafer cassettes 16.

[0144] Slave processor 170 within slave controller 140 of interfacemodule control 110 may operate and monitor the function of the interfacemodules 38, 39. In particular, slave processor 170 may operate doors 35,36 for providing access into the processing tool 10 via ports 32, 33.Alternatively, master control 100 may operate doors 35, 36.

[0145] Referring to FIG. 31, an embodiment of the interface modulecontrol portion for controlling wafer interface module 38 is discussed.In particular, the slave processor 170 is coupled with servo controller175. Either slave processor 170 or a processor on board servo controller175 may operate the components of interface module 38. In particular,slave processor 170 may control turnstile motor 185 for operating rotatefunctions of turnstile 40 moving wafer cassettes 16 between a loadposition and a transfer position. Incremental turnstile encoder 190monitors the position of turnstile 40 and provides position data toslave processor 170. Alternatively, servo controller 175 may include aprocessor for reading information from turnstile encoder 190 andcontrolling turnstile motor 185 in response thereto. Servo controller175 may alert slave processor 170 once turnstile 40 has reaches adesired position.

[0146] Each wafer cassette turnstile 40 includes a motor for controllingthe positioning of saddles 45, 46 connected thereto. The slave processor170 may control the position of saddles 45, 46 through operation of theappropriate saddle motor 186 to orient wafer cassettes 16 attachedthereto in one of a vertical and horizontal orientation. Incrementalsaddle encoders 191 are preferably provided within each wafer cassetteturnstile 40 for providing position information of the saddles 45, 46 tothe respective slave processor 170.

[0147] Either slave processor 170 or servo controller 175 may beconfigured to control the operation of the wafer cassette elevator 42for transferring a wafer cassette 16 between either the exchangeposition and the extraction position. The slave processor 170 may becoupled with an elevator lift motor 187 and elevator rotation motor 188for controlling the elevation and rotation of elevator 42 and elevatorsupport 47. Incremental lift encoder 192 and incremental rotationencoder 193 may supply elevation and rotation information of theelevator 42 and support 47 to slave processor 170.

[0148] Absolute encoders 199 may be utilized to notify slave processorof extreme conditions such as when elevator support 47 reaches a maximumheight. Elevator lift motor 187 may be shut down in response to thepresence of an extreme condition by absolute encoder 199.

[0149] Wafer Cassette Tray

[0150] A wafer cassette tray 50 for holding a wafer cassette 16 is shownin detail in FIG. 9. Each cassette tray 50 may include a base 51 and anupright portion 54 preferably perpendicular to the base 51. Two lateralsupports 52 may be formed on opposing sides of the base 51 and extendupward therefrom. Lateral supports 52 assist with maintaining wafercassettes 16 thereon in a fixed position during the movement, rotationand exchange of wafer cassettes 16. Each lateral support 52 contains agroove 53 preferably extending the length thereof configured to engagewith the forks of saddles 45, 46.

[0151] The wafer cassette trays 50 are preferably utilized during thehandling of wafer cassettes 16 within the wafer cassette interfacemodules 38, 39 where the wafer cassettes 16 are transferred from a loadposition to an extraction position providing access of the semiconductorwafers W to wafer transport units 62, 64 within the conveyor 60.

[0152] Electroplating Station

[0153]FIG. 33 shows principal components of a second semiconductorprocessing station 900 is specifically adapted and constructed to serveas an electroplating station. The two principal parts of processingstation 900 are the wafer rotor assembly, shown generally at 906, andthe electroplating bowl assembly 303.

[0154] Electroplating Bowl Assembly 303

[0155]FIG. 33 shows an electroplating bowl assembly 303. The processbowl assembly consists of a process bowl or plating vessel 316 having anouter bowl side wall 317, bowl bottom 319, and bowl rim assembly 917.The process bowl is preferably circular in horizontal cross-section andgenerally cylindrical in shape although other shapes may be possible.

[0156] The bowl assembly 303 includes a cup assembly 320 which isdisposed within a process bowl vessel 317. Cup assembly 320 includes afluid cup portion 321 holding the chemistry for the electroplatingprocess. The cup assembly also has a depending skirt 371 which extendsbelow the cup bottom 323 and may have flutes open therethrough for fluidcommunication and release of any gas that might collect as the chamberbelow fills with liquid. The cup is preferably made from polypropyleneor other suitable material.

[0157] A lower opening in the bottom wall of the cup assembly 320 isconnected to a polypropylene riser tube 330 which is adjustable inheight relative thereto by a threaded connection. A first end of theriser tube 330 is secured to the rear portion of an anode shield 393which supports anode 334. A fluid inlet line 325 is disposed within theriser tube 330. Both the riser tube 330 and the fluid inlet line aresecured with the processing bowl assembly 303 by a fitting 362. Thefitting 362 can accommodate height adjustment of both the riser tube andline 325. As such, the connection between the fitting 362 and the risertube 330 facilitates vertical adjustment of the anode position. Theinlet line 325 is preferably made from a conductive material, such astitanium, and is used to conduct electrical current to the anode 324, aswell as supply fluid to the cup.

[0158] Process fluid is provided to the cup through fluid inlet line 325and proceeds therefrom through fluid inlet openings 324. Plating fluidthen fills the chamber 904 through opening 324 as supplied by a platingfluid pump (not shown) or other suitable supply.

[0159] The upper edge of the cup side wall 322 forms a weir which limitsthe level of electroplating solution within the cup. This level ischosen so that only the bottom surface of wafer W is contacted by theelectroplating solution. Excess solution pours over this top edgesurface into an overflow chamber 345. The level of fluid in the chamber345 is preferably maintained within a desired range for stability ofoperation by monitoring the fluid level with appropriate sensors andactuators. This can be done using several different outflowconfigurations. A preferred configuration is to sense a high levelcondition using an appropriate sensor and then drain fluid through adrain line as controlled by a control valve. It is also possible to usea standpipe arrangement (not illustrated), and such is used as a finaloverflow protection device in the preferred plating station. Morecomplex level controls are also possible.

[0160] The outflow liquid from chamber 345 is preferably returned to asuitable reservoir. The liquid can then be treated with additionalplating chemicals or other constituents of the plating or other processliquid and used again.

[0161] In the preferred uses according to this invention, the anode 334is a consumable anode used in connection with the plating of copper orother metals onto semiconductor materials. The specific anode will varydepending upon the metal being plated and other specifics of the platingliquid being used. A number of different consumable anodes which arecommercially available may be used as anode 334.

[0162]FIG. 33 also shows a diffusion plate 375 provided above the anode334 for providing a more even distribution of the fluid plating bathacross the Wafer W. Fluid passages are provided over all or a portion ofthe diffusion plate 375 to allow fluid communication therethrough. Theheight of the diffusion plate is adjustable using diffuser heightadjustment mechanisms 386.

[0163] The anode shield 393 is secured to the underside of theconsumable anode 334 using anode shield fasteners 394 to prevent directimpingement by the plating solution as the solution passes into theprocessing chamber 904. The anode shield 393 and anode shield fasteners394 are preferably made from a dielectric material, such aspolyvinylidene fluoride or polypropylene. The anode shield isadvantageously about 2-5 millimeters thick, more preferably about 3millimeters thick.

[0164] The anode shield serves to electrically isolate and physicallyprotect the back side of the anode. It also reduces the consumption oforganic plating liquid additives. Although the exact mechanism may notbe known at this time, the anode shield is believed to preventdisruption of certain materials which develop over time on the back sideof the anode. If the anode is left unshielded, the organic chemicalplating additives are consumed at a significantly greater rate. With theshield in place, these additives are not consumed as quickly.

[0165] Wafer Rotor Assembly

[0166] The wafer rotor assembly 906 holds a wafer W for rotation withinthe processing chamber 904. The wafer rotor assembly 906 includes arotor assembly 984 having a plurality of wafer-engaging fingers 979 thathold the wafer against features of the rotor. Fingers 979 are preferablyadapted to conduct current between the wafer and a plating electricalpower supply and may be constructed in accordance with variousconfigurations to act as current thieves.

[0167] The various components used to spin the rotor assembly 984 aredisposed in a fixed housing 970. The fixed housing is connected to ahorizontally extending arm 909 that, in turn, is connected to avertically extending arm. Together, the arms 908 and 909 allow theassembly 906 to be lifted and rotated from engagement with the bowlassembly to thereby present the wafer to the wafer conveying assembly 60for transfer to a subsequent processing station.

[0168] Alternative Lift and Tilt Mechanism

[0169] Turning now to FIG. 34, that figure shows an embodiment of alift/tilt assembly 6000. The components of the lift/tilt assembly 6000are preferably formed from hard black anodized aluminum, althoughstainless steel may also be used. The lift/tilt assembly 6000 may beused to load wafers into the interface modules 38,39 and may be usedinstead of, or in conjunction with, a wafer cassette turnstile 40 or 41described above. Before the operation of the lift/tilt assembly 6000 isdiscussed, the component parts of the lift/tilt assembly 6000 will bedescribed.

[0170] Referring again to FIG. 34, the lift/tilt assembly 6000 includesa nest 6002 coupled to a linear way 6004 that is driven by a motor 6006.The term “nest” generally indicates a platform on which a wafer bearingcassette may be loaded. The lift/tilt assembly 6000 includes a linearencoder LED assembly 6008 and a linear encoder CCD assembly 6010. Inaddition, the lift/tilt assembly 6000 preferably includes a tube sensor6012, a tube sensor receiver 6014, and an H-bar sensor (not shown)located in the nest 6002. The nest 6002 moves between two orientationsgenerally described as wafer-horizontal and wafer-vertical. As shown inFIG. 60, the nest 6002 is in the wafer-horizontal position.

[0171] Turning now to FIG. 35, another view of the lift/tilt assembly6000 is shown. A wafer cassette 6100, holding a number of wafers 6102,rests in the nest 6002. As will be described in more detail below withrespect to the operation of the lift/tilt assembly 6000, the nest 6002in FIG. 61 is oriented in the wafer-vertical position.

[0172] Referring to FIGS. 36-38, three section views of the lift/tiltassembly 6000 are shown. FIGS. 36-38 illustrate operation of theassembly at three translational operating points and show the resultantpositioning of the nest 6002 as it moves from a near wafer-verticalposition (FIG. 36) to a near wafer-horizontal position (FIG. 38). Thelinear way 6004 includes a fixed frame 6208 and a movable frame 6210.The movable frame 6210 may be implemented as any structure mounted on amoving portion of the linear way 6004. For example, the movable frame6210 may be mounted to a carriage that moves linearly under control ofthe motor 6006. The linear way 6004 may be implemented, for example,with a linear motion guide available from THK America, 200 E. CommerceDrive, Schaumburg, Ill. 60173.

[0173] Connected to the nest 6002 is a lever 6200 including a leverwheel or ball bearing 6202 which rides on a guide, for example, ramp6204. The guide is generally implemented as a smooth surface over whichthe ball bearing 6020 may roll during transition between thewafer-horizontal position and the wafer-vertical position. A torsionspring assembly 6206 provides forcing bias on the nest 6002 which helpstransition the nest 6002 between a wafer-vertical position and awafer-horizontal position (where the nest 6002 may be supported by ahard stop 6212) as will be explained in more detail below. The ramp 6204is mounted in a fixed position on top of the fixed frame 6208 while thetorsion spring assembly 6206 is mounted on the movable frame 6210.

[0174] In operation, as noted above, a lift/tilt assembly 6000 is usedto load wafers into the interface modules 38, 39 and may reside behindpowered doors 35 or 36. During the loading or unloading process, thelift/tilt assembly 6000 returns to the wafer-vertical position shown inFIG. 61. A sensor connected to the powered doors 35, 36 may be used toinform the control system 100 (FIGS. 14-21) that the powered doors 35,36, are in fact open, and that the lift/tilt assembly 6000 should not beallowed to move (thereby providing a safety interlock mechanism).

[0175] For loading operations, the nest 6002 preferably returns to awafer-vertical position which is approximately 15 degrees above truevertical. The wafer-vertical position thereby holds the nest 6002 at asmall slope down which the wafer cassette 6100 may slide into acompletely loaded position. Furthermore, the preferred wafer-verticalposition helps eliminate a contaminant generating condition related tothe wafers 6102. Because the wafers 6102 fit loosely in the wafercassette 6100, the wafers 6102 tend to rattle when in a strictlyvertical orientation. When the wafers 6102 rattle, they tend to generateparticles that may contaminate the processing environment. Thus, thepreferred wafer-vertical position prevents the wafers 6102 from restingin a true vertical position and generating particles.

[0176] Referring again to FIG. 36-38, those figures show the motion ofthe nest 6002 between its wafer-vertical position (FIG. 36) and itswafer-horizontal position (FIG. 38). The movable frame 6210 of thelinear way 6004 moves linearly along a track under control of the motor6006, a ball screw and linear bearings (not shown). The motor 6006generally includes a rotary encoder, typically an optical encoder, thatproduces a relative encoder output including a predetermined number ofpulses (for example, 2000) per motor revolution. The pulses indicate thenumber of revolutions (or fractions of revolutions) through which themotor has turned. The pulses may therefore be converted to a lineardistance by taking into account the coupling between the motor 6006 andthe linear way 6004. The pulses may be fed back to the control system100, or may be processed by a local microcontroller which coordinatesthe movement of the linear way 6004.

[0177] In addition to the relative encoder output that the motorproduces, the lift/tilt assembly 6000 may optionally include a linearencoder LED assembly 6008 and a linear encoder CCD assembly 6010 whichoperate together as an linear absolute encoder. Referring again to FIG.35, the LED assembly 6008 is shown and includes a series of LEDs 6104and corresponding light transmission slits 6106. The linear encoder CCDassembly 6010 includes a CCD module 6110 and associated CCD controlcircuitry 6108.

[0178] Each individual LED 6104 produces a light output which isdirected through a corresponding slit 6106. Each slit 6106 only allowslight to pass through that is produced by its corresponding LED, and tothat end may, for example, be 15 mils or less in diameter. The LEDs 6104are mounted on the fixed frame 6208, while the linear encoder CCDassembly 6010 is mounted on the movable frame 6210. The CCD module 6110moves along a path underneath the slits 6106 and therefore may detectlight produced by the LEDs 6104. Therefore, as the moveable frame 6210translates up or down the linear way 6004, the CCD control circuitry6010 may monitor the number and position of the light sources it detectsand may provide feedback as to the absolute vertical position of themoveable frame 6210. Commercially available CCD modules providesufficient resolution to determine the vertical position of the moveableframe 6210 to better than 10 mil resolution. The control system 100, mayuse feedback from the CCD control circuitry 6010, for example, as adouble check against the rotary encoder output produced by the motor6006.

[0179] As the moveable frame 6210 advances up the linear way 6004, thenest 6002 moves up with the torsion spring assembly 6206 above from theramp 6204. The torsion spring exerts a force on the nest 6002 and lever6200, causing the nest 6002 to rotate around the torsion spring assembly6206 and into the wafer-horizontal position. During the transition fromthe wafer-vertical position to the wafer-horizontal position, the ballbearing 6202 and lever 6200 ride on the ramp 6204 which helps ensure asmooth transition between the two positions. When the nest 6002 reachesthe wafer-horizontal position, a hard stop 6212 is provided thatprevents further rotation of the nest 6002 around the torsion springassembly 6206.

[0180] It is noted that other devices may be used to induce rotationalmovement of the nest 6002. For example, a nest motor may produce torqueon a shaft rigidly connected to the nest 6002 to cause it to rotatebetween the wafer-vertical and wafer-horizontal orientations. The torqueproducing nest motor may operate under general program control of thecontrol system 100 to produce rotation in the nest 6002 as the moveableframe 6210 translates.

[0181] The torsion spring in the torsion spring assembly 6206 providesthe force required to lift a wafer cassette 6100, including wafers 6012,from the wafer-vertical position to the wafer-horizontal position. Tothat end, the torsion spring is preferably formed from music wire, butmay also be formed from stainless steel. When the motor 6006 activatesto draw the movable frame 6210 back down the linear way 6004, the nest6002 rotates in the opposite direction around the torsion springassembly 6206. The level 6200 and ball bearing 6202 move smoothly alongthe ramp 6204 in the opposite direction to return the nest 6002 to thewafer-vertical position. At the wafer-vertical position, the lever 6200provides a stop that holds the nest 6002 at approximately 15 degreesfrom true vertical (FIG. 36). It is noted that linear movement in thelinear way 6004 accomplishes both translational and rotational movementsin the nest 6002.

[0182] Additional sensors may be provided on the lift/tilt assembly 6000to provide feedback regarding the status of the nest 6002 and the wafercassette 6100. As noted above, an H-bar sensor may be located in avariety of positions in the nest 6002. A wafer cassette 6100 generallyincludes two registration bars of vertical length and a registrationcross bar of horizontal length. The bars are collectively referred to asan “H-bar”. The H-bar sensor may be implemented as an optical sensor andreceiver pair or as a mechanical switch sensor that indicates when theH-bar, and therefore a wafer cassette 6100, is present in the nest 6002.An optical H-bar sensor may operate, for example, by providing anoptical transmission and reception path which is broken by an H-bar on aloaded wafer cassette 6100, while a mechanical H-bar sensor may operateby providing a mechanical switch that is triggered when the wafercassette 6100 is inserted in the nest 6002.

[0183] Because each wafer cassette manufacturer may control the locationof the H-bar and because the wafer cassette may vary in constructionbetween manufacturers, the nest 6002 may be configured with differentH-bar assemblies that accept the wafer cassettes 6100 of variousmanufacturers. The H-bar sensor, in turn, is not restricted to anyparticular position on the nest 6002, but may be implemented as anyoptical or mechanical sensor positioned to detect the H-bar on aparticular wafer cassette 6100. FIG. 39 shows one example of an H-barassembly 6500.

[0184] The H-bar assembly 6500 includes a horizontal track 6502, a firstvertical track 6504, and a second vertical track 6506. The H-barassembly 6500 also includes an optical sensor 6508 and an opticalemitter 6510. An H-bar on a wafer cassette 6100 fits into the horizontaltrack 6502 and the vertical tracks 6504, 6506. As shown in FIG. 39, theoptical emitter 6510 is positioned to emit energy along the horizontaltrack 6502. The optical sensor is positioned across the horizontal track6502 to receive the emitted energy. The optical sensor 6508 maytherefore detect the presence or absence of an H-bar of a wafer cassette6100 by determining whether it is receiving energy emitted by theoptical emitter 6510. The H-bar assembly may be mounted to the nest6002, for example, across the area 6600 shown in FIG. 40.

[0185] The lift/tilt assembly 6000 may also provide a tilt positionsensor. As noted above, the torsion spring assembly 6206 provides theforce required to move the wafer cassette 6100 from a wafer-verticalorientation to a wafer-horizontal position. The tilt position sensorprovides feedback that indicates when the nest 6002 has reached thewafer-horizontal position. FIG. 40 shows one possible implementation ofa tilt sensor on a nest 6002.

[0186]FIG. 66 shows the top side 6602 of the nest 6002 and the bottomside 6604 of the nest 6002 and a tilt sensor 6604. The tilt sensor may,for example, connect to the bottom side 6604 at location 6606. The tiltsensor 6604 includes an emitter 6610 and a sensor 6612. An interrupterflag 6614 is mounted on the moveable frame 6210. As shown in FIG. 66,the emitter 6610 and the sensor 6612 are placed so that an unbrokenoptical path exists between the transmitter and receiver while the nest6002 is rotated out of the wafer-horizontal orientation. The emitter6610 and the sensor 6612 are also placed on the nest 6002 such that whenthe nest 6002 rotates into the wafer-horizontal orientation, theinterrupter flag 6614 connected to the moveable frame 6210 breaks thepath between the emitter 6610 and the sensor 6612.

[0187] A tilt sensor may also be implemented as a mechanical switchlocated on the hard stop 6212. The mechanical switch may then betriggered by the nest 6002 coming into the wafer-horizontal position atthe hard stop 6212. Feedback from either the mechanical switch or theoptical sensor may be used to determine when the torsion spring assembly6206 is wearing out, or has failed altogether (for example, the controlsystem 100 may detect that after a sufficient number of motor 6006revolutions, that the tilt sensor does not indicate wafer-horizontalposition for the nest 6002).

[0188] Referring again to FIG. 35, that figure illustrates the positionsof a tube sensor 6012 and a tube sensor receiver 6014. The tube sensor6012 houses an emitter, for example an optical emitter, that transmits abeam down to a tube sensor receiver 6014. As shown in FIG. 35, the tubesensor 6012 is oriented along the right hand side of the lift/tiltassembly 6000. FIG. 34, however, illustrates that a tube sensor 6012 mayalso be oriented along the left hand side of the lift/tile assembly6000. The left hand orientation includes a left hand tube sensorreceiver 6014 provided underneath the tube sensor 6012 (FIG. 34).

[0189] Referring again to FIG. 61, the tube sensor 6012 may detect whenwafers 6102 are improperly seated in the wafer cassette 6100. Forexample, wafers that have become dislodged and that therefore extend outof the wafer cassette 6102 will block the sensor receiver 6104. Becausedislodged wafers may catch on an exposed surface on the lift/tiltassembly 6000, the possibility exists that a dislodged wafer may bebroken by vertical movement of the moveable frame 6210. Thus, when theoutput of the sensor receiver 6104 indicates a blocked condition, thecontrol system 100 may respond, for example, by generating an errordisplay, or by directing the wafer transport units 62, 64 to avoidprocessing the dislodged wafer. The control system 100 may also respondby returning the nest 6002 to the wafer-vertical position in an attemptto move the dislodged wafer back into place in the wafer cassette 6100.Note that, in general, the tube sensor 6012 provides the most meaningfulfeedback when the nest 6002 is in the wafer-horizontal orientation.

[0190] Each of the sensors described above may be connected to thecontrol system 100 which may in response exercise intelligent controlover the lift/tilt assembly 6000. It will be recognized that the preciseplacement of the sensors may vary widely while allowing the sensors toperform their intended functions. Thus, for example, it may be possibleto mount the tube sensor receiver on a portion of the moveable frame6210 rather than the nest 6002. Furthermore, an additional sensorsystem, a laser mapping unit, may be provided for indexing the wafers,or absence of wafers, in a wafer cassette 6100.

[0191] Referring to FIG. 41, a laser mapping system 6700 in shown thatincludes optical transmitters 6702 and 6704 and optical receivers 6706and 6708. The optical receivers 6706 and 6708 are placed behind anopening 6710 in the nest 6002. The optical receivers 6706 and 6708 andthe optical transmitters 6702 and 6704 may be mounted on a fixedstructure 6712 supported independently of the lift/tilt assembly 6000.

[0192] The optical transmitters 6702 and 6704 emit radiation, forexample at visible or infrared wavelengths, along the nest 6002 andthrough the opening 6408. The optical receivers 6706 and 6708 produceoutputs responsive to the amount of emitted radiation they detect. Thenest 6002 moves vertically through the laser mapping system 6700 duringthe operation of the laser mapping system 6700. In particular, after thenest 6002 has reached the wafer-horizontal position, the moveable frame6208 may continue to move the nest 6002 (which rests against the hardstop 6212) vertically.

[0193] As the nest 6002 continues to move vertically, a laser mappingfunction takes place during which each of the wafers 6012 passes, inturn, in front of the optical transmitters 6704 and 6706. The radiationemitted by the optical transmitters 6705 and 6706 is thereforealternately prevented and allowed to reach the optical receivers 6706and 6708. The control system 100 may, therefore, monitor the opticalreceiver 6706 and 6708 outputs, the motor 6006 rotary encoder output,and optionally the linear encoder CCD assembly 6010 outputs to determinethe presence or absence of wafers 6012 and the position of the presentor absent wafers 6012 in the wafer cassette 6100. A single opticaltransmitter and receiver pair is sufficient to perform the laser mappingfunction, although additional individual optical transmitters, such asthe optical transmitter 6704, may be provided to check exclusively forthe presence of wafers or to check exclusively for the absence ofwafers, for example.

[0194] After the laser mapping procedure has completed, the controlsystem 100 may continue to raise the nest 6002 above the opticaltransmitters 6702 and 6704 so that the wafer transport units 62, 64 canaccess individual wafers 6012. FIG. 42 illustrates the nest 6002 in aposition above the laser mapping system 6700. The control system 100 maythen instruct the wafer transport units 52, 54 to operate on the wafers6102 that the laser mapping system has detected and adjust the height ofthe nest 6002 so that the wafer transport units 52,52 may accessindividual wafers 6012. The control system 100 may also instruct thewafer transport units 52, 54 to skip gaps in wafers 6102 that may bepresent in the wafer cassette 6100 or may instruct the wafer transportunits 52, 54 to use gaps in the wafer cassette 6100 to store processedwafers.

[0195] Numerous modifications may be made to the foregoing systemwithout departing from the basic teachings thereof. Although the presentinvention has been described in substantial detail with reference to oneor more specific embodiments, those of skill in the art will recognizethat changes may be made thereto without departing from the scope andspirit of the invention as set forth in the appended claims.

What is claimed:
 1. A lift/tilt assembly for use in a semiconductorwafer processing device, said lift/tilt assembly comprising: a linearway comprising a fixed frame and a moveable frame; a nest rotatablyconnected to said moveable frame, said nest rotating between awafer-horizontal orientation and a wafer-vertical orientation; a motorcoupled to said linear way, and a lever connected to said nest, saidlever providing an offset from true vertical for said nest when saidnest is in said wafer-vertical orientation.
 2. The lift/tilt assembly ofclaim 1, further comprising a torsion spring assembly connected to saidmoveable frame, said torsion spring assembly comprising a torsion springexerting a forcing bias against said nest.
 3. The lift/tilt assembly ofclaim 1, further comprising a nest motor connected to said moveableframe, said nest motor rigidly connected to said nest to producerotation in said nest.
 4. The lift/tilt assembly of claim 1, furthercomprising a guide connected to said fixed frame and a ball bearingconnected to said lever, said guide including a smooth surface overwhich said ball bearing may move.
 5. The lift/tilt assembly of claim 4,wherein said guide is a ramp.
 6. The lift/tilt assembly of claim 1,further comprising a linear encoder LED assembly mounted to said fixedframe and a linear encoder CCD assembly mounted to said moveable frame.7. The lift/tilt assembly of claim 1, further comprising a tilt sensorconnected to said nest and to said moveable frame.
 8. The lift/tiltassembly of claim 1, further comprising a H-bar sensor connected to saidnest.
 9. The lift/tilt assembly of claim 1, further comprising a tubesensor connected to said moveable frame and a tube sensor receiverconnected to said nest.
 10. The lift/tilt assembly of claim 1, furthercomprising a laser mapping unit comprising: at least one transmitter; atleast one receiver; said transmitter disposed to transmit energy througha wafer cassette located in said nest, and said receiver disposed toreceive said energy transmitted by said transmitter.
 11. The lift/tiltassembly of claim 1, wherein said transmitter transmits optical energyand wherein said receiver receives optical energy.